The present invention relates generally to railroad right-of-way maintenance machinery, and specifically to machinery used for driving fasteners into rail ties for securing rail tie plates and rails to the ties.
Rail fasteners as contemplated herein include cut spikes, lag screws, hairpin spikes and other types of rail fasteners used for retaining tie plates upon ties, and rails upon tie plates, as are known to skilled practitioners. In some cases in the specification, “spikes” may be used interchangeably with “rail fasteners”. The use of the term “spikes” is not intended to limit the scope of the present invention.
During the course of railroad maintenance work, it is common that existing rail fasteners are removed for replacement of rail ties, tie plates, rails and for other maintenance operations. Once the desired maintenance is complete, the fasteners need to be reinstalled. Several types of rail fastener applicators or drivers are known, and suitable models are described in commonly assigned U.S. Pat. Nos. 4,579,061; 4,777,885; 5,191,840 and 5,671,679, all of which are incorporated by reference herein, and all of which are assigned to Nordco Inc. of Milwaukee, Wis.
Such rail fastener driving machines typically include a frame which is either self-propelled or towable along the track, a rail fastener driving apparatus with a fastener driving mechanism such as a fluid power cylinder provided with a reciprocating element for impacting a fastener and driving it into a tie, a fastener magazine configured for accommodating a plurality of rail fasteners and feeding them sequentially for driving by the element, a fastener feeder mechanism configured for conveying fasteners sequentially from the magazine to a location in operational relationship to the driving element.
Such devices typically have a travel position, where the fastener feeder mechanism is held sufficiently above the track to avoid damage by obstacles including the track itself. In addition, during operation, the units typically move between a first or fastener loading position, and a fastener driving position. It is important, for maintaining desired productivity rates, that the latter two positions are closer to the track. To avoid damage to the mechanisms, such units are designed for operation so that either travel is prohibited when these mechanisms are in the latter two positions, or the mechanisms automatically rise to the travel position when the unit begins to move to the next location.
While protecting the typically complicated rail fastener handling and driving mechanisms, this operational precautions tend to limit productivity as measured by the rate of fastener-driving by a particular unit.
Thus, there is a need for a rail fastener driving mechanism which enables greater fastener driving productivity while protecting the fastener driving mechanisms.
There is also a need for a rail fastener driving mechanism which is configured so that the unit can be transported along the track with the fastener driving mechanism in a position closer to the track for more rapid fastener driving and greater productivity.